1. Field of the Invention
The present invention relates to filled or extended polyurethane foams containing a polyethylene glycol softening agent. These materials are useful as cushioning materials.
2. Description of the Prior Art
It is known to make highly filled, flexible polyurethane foams which contain relatively high amounts of filler. The filler is added to increase the density of the foam which is used as a cushioning material. This added density acts to reduce the "wing-out" or "butterflying" of the foams which results when a person sits in the center of the foam causing its sides to be raised. The addition of the filler reduces this undesirable "winging-out" of the foams. In addition, the sag factor (ratio of 65% IFD [indentation force deflection]/25% IFD) is increased thereby improving the weight supporting properties of the material which reduces "bottoming out". One example of a prior art patent showing the general type of foams to which the present invention relates is U.S. Pat. No. 3,298,976 to M. H. Rinehart.
The presence of filler in such highly filled flexible polyurethane foams interferes with the normal processing operations needed to produce the foams for example the pouring of a liquid foamable composition onto a conveyor for transfer to the foaming stage can be adversely affected by the presence of high levels of the filler. The catalyst balance of the liquid foamable composition is changed by the "heat sink" effects caused by the high filler loading. It has been common practice in regard to the manufacture of such foams to use relatively high levels of auxiliary blowing agents (e.g. halohydrocarbon auxiliary blowing agents) with a lower level of waterblowing agent in an effort to give greater softness (i.e., lower load bearing characteristics) to the foams while maintaining roughly the same density desired. The use of these higher halohydrocarbon/lower water blowing agent compositions has led to certain disadvantages in the foaming operation, namely, a certain degree of foaming instability as exhibited by the presence of voids, splits, fissures and, in some instances, partial foam collapse.
Hence, a need exists in the art to allow for an additive to give a softer filled polyurethane foam of the aforementioned type while allowing the foamer to utilize generally higher water and lower halohydrocarbon auxiliary blowing agent levels than hitherto possible in achieving such a soft foam.